A conventional pharmaceutical injection device comprises a main body case having an injection needle insertion and retraction opening, a pharmaceutical syringe mounting portion provided inside this main body case, a pharmaceutical syringe mounted to this pharmaceutical syringe mounting portion, a piston provided movably with respect to this pharmaceutical syringe, a drive mechanism that drives this piston, and a controller that is electrically connected to this drive mechanism.
The pharmaceutical syringe has a cylinder and a push-in gasket provided on the rear end side inside this cylinder.
That is, with a conventional pharmaceutical injection device, the pharmaceutical is injected into the body by pushing the push-in gasket with the piston (see Patent Literature 1, for example).